JPH0459942A - Shank material for high speed steel tool - Google Patents

Abstract

PURPOSE:To manufacture a shank material for a high speed steel tool excellent in weldability or the like by preparing a steel having a specified compsn. in which each content of Cr, Si, Mo and Al is prescribed. CONSTITUTION:A steel contg., by weight, 0.40 to 0.80% C, 0.40 to 1.50% Si, 0.20 to 2.00% Mn, 0.10 to 1.50% Ni, 0.50 to 3.00% Cr, 1.0 to 3.00% Mo, <=0.30% V and 0.040 to 0.l00% Al, furthermore contg., at need, 0.02 to 0.30% Nb and the balance Fe with inevitable impurities is prepd. In this way, the shank material excellent in weldability with a high speed steel, high in strength in the weld zone and, furthermore, having sufficient hardness even if heat treatment is executed simultaneously with the high speed steel can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a shank material for end mills, drills, etc., in which the blade material is made of high-speed steel and the shank is welded by various welding methods.

[Prior art]

In cutting tools such as end mills that are manufactured using high-speed steel, the shank is made from low-grade steel such as carbon steel in order to save on the expensive high-speed steel, and the shank is welded using friction welding or flash butt welding. Cost reductions are being achieved by manufacturing so-called composite tools that are joined together.

However, if these materials are heat-treated simultaneously while bonded to high-speed steel, the grains will become coarser and the toughness will decrease. Therefore, in general, only the high-speed steel is first placed in a salt bath, and after a predetermined period of time, the shank portion is A two-stage heat treatment is required.

In addition, in recent years, there has been remarkable development of high-speed steel for cutting difficult-to-cut materials.
Although it has come to be widely used in cutting tools such as end mills, conventional shank materials have low weld strength.
In addition, if heat treatment is performed simultaneously with high-speed steel to improve heat treatment workability, sufficient hardness and strength may not be obtained, causing accidents such as buckling and making the shank unusable. The color of the wood differs, and some have inferior commercial value.

(Problems to be Solved by the Invention) The present invention is inexpensive, has excellent weldability, has high weld strength, and can obtain high hardness of HRC50 or higher even when heat treated simultaneously with high-speed steel. The purpose is to obtain a shank material for high-speed steel tools that has the same shank color and has high commercial value.

[Means to solve the problem]

As a result of intensive research to solve the above problems, the inventors found that
The present invention was completed by discovering that steel having the composition shown below is suitable.

That is, in the present invention, the weight ratio of C is 0.40 to 0°80%.
, Si: 0.40-1.50%, Mn: 0°20-2
．． 00%, Ni; 0.10-1.50%, Cr; 0.
50-3.00%, Mail, 0-3゜00%, V; 0
．． A shank material for a high-speed skin conditioning tool, characterized by containing 30% or less, Al; 0.040 to 0.100%, and further containing Nb; 0.02 to 0.30% as necessary. be.

The present invention is characterized in that a hardness of HRC50 or higher can be obtained even when heat-treated simultaneously with high-speed steel, by combining the effect of Si and Mo and increasing the softening resistance by incorporating Cr.

In addition, by suppressing the Cr content to 3.00% or less, weld cracking between the high-speed steel and the shank material is prevented, and the difference in color between the high-speed steel and the shank material is eliminated even when heat treatment is performed simultaneously. Furthermore, by actively adding AI, defects such as bubbles in the weld are reduced, and the transverse rupture strength of the weld is increased to 320 kgf/mm2 or more.

Therefore, it has higher hardness and weld strength than conventionally used shank materials, and has good heat treatment workability, and can greatly contribute to improving the performance of high-speed steel tools for cutting difficult-to-cut materials. It is.

The reasons for limiting the components of the present invention will be described below.

C; 0.40 to 0.80% C is an essential element that solidly dissolves in the matrix and strengthens the material. It forms carbides with Cr, Mo, etc. to improve wear resistance, and also improves high-speed steel. Even if simultaneous heat treatment is performed, the content must be 0.40% or more to achieve an HRC of 50 or more.
If the content exceeds 0.80%, the toughness will be significantly reduced, so the range of the content was set to 0.40 to 0.80%.

Si: 0.40-1.50% Si is an element necessary for deoxidation and is effective for strengthening the base, and for that purpose it is necessary to contain 0.40% or more, but 1.50% If the content exceeds 0.00, the toughness will drop significantly and decarburization will be accelerated, so the range of the components should be reduced to 0.
The content was set at 40 to 1.50%.

Mn: 0.20-2.00% Mn is an element necessary for deoxidation like Si, and
It is effective in improving hardenability, and for that purpose it must be contained at 0.20% or more, but if it is contained in excess of 2.00%, annealing hardness will increase and workability will decrease, so the component The range was 0.20 to 2°00%.

Ni: 0.10-1.50% Ni is effective in increasing the strength of the matrix, preventing coarsening of crystal grains, and improving toughness, and for this purpose, 0.10%
However, if the content exceeds 1.50%, the hardness and strength will decrease, so the range of the components should be reduced to 0.
．． The content was set at 10 to 1.50%.

Cr: 0.50 to 3.00% Cr improves temper softening resistance and forms carbides to improve wear resistance. It is also an effective element for improving hardenability, and for this purpose it must be contained in an amount of 0.50% or more.
If the content exceeds 0%, weldability deteriorates, so the range of the content was set to 0.50 to 3.00%.

Mo: 1.00-3.00% Mo is an element that increases resistance to temper softening, and for this purpose it must be contained at 1.00% or more, but if it is contained over 3.00%, the toughness Since this decreases, the component range is set to 1.00 to 3.00%.

V: 0.30% or less V is an element that contributes to improving strength and temper softening resistance, but it is expensive, so it was set to 0.30% or less.

Al: 0.040-0.100% Al is an element effective in reducing air bubbles that occur in the weld between high-speed steel and shank material, and for this purpose it must be contained at 0.040% or more. If the content exceeds 0.100%, nonmetallic inclusions will increase, so the component range should be reduced to 0.100%.
040% to 0.100%.

Nb: 0.02 to 0.30% Nb has the effect of preventing coarsening of crystal grains and increasing toughness, and for this purpose it is necessary to contain 0.02% or more, but if it exceeds 0.30% Even if it is contained, the effect is saturated, so the range of the component was set to 0.02 to 0.630%.

〔Example〕

Next, the features of the present invention will be explained using examples.

The chemical components of Examples of the present invention are shown in Table 1.

Table 1 (blank below) In Table 1, A-E steel is the invention network, and A-C steel is the first steel.
The invention steels, D and E steels are the second invention network.

F-Jl is comparative steel and Km is JIS conventional steel.

It is 555C.

The hardness, weldability, color of the weld shank material, and weld transverse rupture strength of these steels after heat treatment were investigated.

Hardness is 1190 in vacuum, same as heat treatment of high speed steel.
After holding at 'C for 15 minutes, gas cooling and quenching, and 5 minutes in vacuum.
After holding at 60°C for 2 hours and then repeating air cooling tempering three times, the hardness was measured using a Rockwell hardness meter.

Weldability was determined by friction welding a material with a diameter of 16 mm with high-speed steel of the same diameter, and after processing it into an end mill, the presence or absence of defects such as cracks in the welded area was observed.

Next, the end mill whose weldability was investigated was heat treated under the same conditions as for hardness measurement, and after visually observing the color of the high-speed steel and shank material, it was subjected to a 4-point bending bending test to measure the transverse rupture strength of the weld. did.

These results are shown in Table 2.

Table 2 Regarding the color tone in Table 2, there is no difference in color between high-speed steel and shank material at all, marked with ○, with a slight difference in color, marked with Δ, and with a clear difference in color and color marked with ∆. Represented by an x mark.

Comparative steel #F has low hardness and transverse rupture strength because of its low C content, and comparative steel G has defects in welds because it has a high Cr content, and its color and transverse rupture strength are also inferior. Comparative steel H has a high Ni content and a low AI content, so its hardness is low, there are defects in welds, and its transverse rupture strength is low.

Comparative steel J has a high MO content, so its color and transverse rupture strength are inferior, and its hardness and transverse rupture strength are lower than conventional steels. In other words, it is clear that the steel of the present invention is superior to comparative steels and conventional steels in terms of hardness, weldability, color, and transverse rupture strength of welded parts.

〔Effect of the invention〕

As explained above, the present invention has discovered a material suitable as a shank material for high-speed steel tools, and its characteristics include excellent weldability with high-speed steel, high weld strength, It is a material that has many advantages, such as being sufficiently hard and having a good color even when heat-treated simultaneously with high-speed steel, and having excellent commercial value and being relatively inexpensive.It is suitable for cutting difficult-to-cut materials. This will greatly contribute to improving the performance of high-speed steel tools.

Claims (2)

[Claims] (1) Weight ratio: C: 0.40-0.80%, Si
;0.40-1.50%, Mn;0.20-2.00%
, Ni; 0.10-1.50%, Cr; 0.50-3.
00%, Mo; 1.00-3.00%, V; 0.30%
The following is a shank material for a high-speed steel tool, characterized in that it contains Al; 0.040 to 0.100%, and the remainder consists of Fe and inevitable impurities. (2) C: 0.40-0.80%, Si by weight ratio
;0.40-1.50%, Mn;0.20-2.00%
, Ni; 0.10-1.50%, Cr; 0.50-3.
00%, Mo; 1.00-3.00%, V; 0.30%
Below, Al: 0.040-0.100%, Nb: 0.0
A shank material for a high-speed steel tool, characterized in that it contains 2 to 0.30% of Fe, and the remainder consists of Fe and unavoidable impurities.